John-Allen,

Since you are doing a clean install, I think I would just start all over with the Dell Reinstallation CD for Windows XP SP2.  I assume that you have the drivers CD for the 8100.  If not, 8100 drivers are located here:   http://support.dell.com/support/downloads/driverslist.aspx?c=us&l=en&s=gen&ServiceTag=&SystemID=INS_PNT_P3CT_8100&os=WW1&osl=en&catid=&impid=

The correct order to install the drivers is here:   http://support.dell.com/support/topics/global.aspx/support/dsn/en/document?c=us&docid=1A0C0937D62A8739E0401E0A55174744&l=en&s=gen

Please note under the Communications drivers that the Inspiron 8100 could possibly have a MiniPCI ethernet/modem combo card.  Installing the wrong communications driver could result in the Ethernet working, but not the modem.

Hope this information helps.

Tony